Experiences of early neglect have pernicious effects on young children's developing brain and behavioral systems. An intervention for neglecting parents, Attachment and Biobehavioral Catch-up, was developed to help parents provide synchronous, nurturing, and non-frightening care to infants and toddlers. As expected, this intervention proved effective in a randomized clinical trial in enhancing attachment security, emotion expression, and physiological regulation among young children. In this competitive renewal, the effects of this intervention on children's functioning in key middle childhood tasks will be examined. First, children in middle childhood need to be able to control or regulate behavior, inhibiting a dominant response. Failure to develop inhibitory control results in problems functioning in both classroom and peer settings. Second, in middle childhood, children need to have the capacity to regulate emotions, controlling the expression of emotions such as frustration or disappointment where it is appropriate to do so. A third key task for middle childhood is developing positive relationships with peers, which affects well-being across domains. Finally, children need to adequately regulate physiology, which although not apparent to observers, has effects on health and well-being. These key domains, inhibitory control, emotion regulation, peer relations, and physiological regulation, are therefore the outcomes assessed in this study. The children followed in this competitive renewal will include 210 children, at least 140 of whom were originally enrolled in the randomized clinical trial testing th efficacy of the Attachment and Biobehavioral Catch-up Intervention, and 70 low-risk comparison children matched for age, ethnicity, and gender. Children will be assessed when they are 8, 9, and 10 years old because this is an age-range when regulatory capabilities have typically consolidated, and demands for self-regulation are high. Inhibitory control will be assessed through behavioral tasks and through event-related potentials (which measures brain activity). Emotion regulation will be assessed through tasks that require children to regulate or control the expression of affect under challenging conditions. Peer relations will be assessed through teacher report, and peer simulation and attributional bias tasks. Physiological regulation will be assessed through measurement of the hormone cortisol. Children whose parents received the Attachment and Biobehavioral Catch-up Intervention and low-risk comparison children are expected to show stronger inhibitory control, better emotion regulation, more appropriate and less aggressive behaviors with peers, and more normative cortisol production, when compared with children whose parents participated in the control intervention.